1. Field of the Invention
The present invention relates to a zoom lens.
2. Description of the Related Art
In recent years, further reductions in size and increased power are demanded of digital cameras and the like. To address these demands, a compact, high power zoom lens is proposed in Japanese Patent Application Laid-Open Publication Nos. 2008-176230 and 2008-185782, for example.
The zoom lenses recited in Japanese Patent Application Laid-Open Publication Nos. 2008-176230 and 2008-185782 are high power zoom lenses that include at least 4 lenses, a positive lens, a negative lens, and two positive lenses, sequentially from an object side. In particular, the zoom lens recited in Japanese Patent Application Laid-Open Publication No. 2008-176230 realizes an angle of view that exceeds 77° at the wide angle edge and a zoom ratio of approximately 9.4. Further, the zoom lens recited in Japanese Patent Application Laid-Open Publication No. 2008-185782 realizes an angle of view that exceeds 61° at the wide angle edge and a zoom ratio of approximately 9.5.
Although the zoom lenses recited in Japanese Patent Application Laid-Open Publication Nos. 2008-176230 and 2008-185782 achieve zoom ratios of 9 or greater, the zoom lenses have a relatively large lens diameter and thus, are not applicable to imaging apparatuses for which greater compactness is demanded. Furthermore, the angle of view is less than 80°, which is narrow and insufficient.
Moreover, the size of the zoom lenses when retracted is too large for application to imaging apparatuses for which reductions in size are demanded. In addition, it cannot be said that the optical performance of these lenses is sufficient.